The fountain darter (''Etheostoma fonticola'') is a species of freshwater ray-finned fish, a darter from the

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

Etheostomatinae Etheosomatidae is a species rich subfamily of freshwater ray-finned fish, the members of which are commonly known as the darters. The subfamily is part of the family Percidae which also includes the perches, ruffes and pikeperches. The famil ...

, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is found in the

headwater The headwaters of a river or stream is the farthest place in that river or stream from its estuary or downstream confluence with another river, as measured along the course of the river. It is also known as a river's source. Definition The ...

s of only two rivers in Texas, United States: the Comal River and the

San Marcos River The San Marcos River rises from the San Marcos Springs, the location of Aquarena Springs, in San Marcos, Texas. The springs are home to several threatened or endangered species, including the Texas blind salamander, fountain darter, and Texas wi ...

. It is generally smaller than long and feeds on small invertebrates. It is a federally listed

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

of the United States and is also listed as endangered by the

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

Distribution and habitat

The fountain darter is known from only two locations, primarily the headwaters of the spring-fed San Marcos River, having been observed as far as 1.25 miles downstream, as well as the upper reaches of the Comal River in central Texas. Its geographic isolation is reflective of its incredibly specific habitation preferences which demand conditions which can only be found in these two Texas river headwaters. In these unique locations they can be observed in open areas created by a medium current at depths of 3–5 feet near the outlets of contributing spring heads with rates of flow low enough to retain a layer of percolating sand. These springs can be found adjacent to the main springs that deliver the tremendous volumes of cool, perfectly clear water that forms each river. They require a stable water temperature, within the low 70s, year round which the springs provide. These two locations are uniquely suited habitat as these ecosystems’ diversity and ultra-high densities of plant and animal life are unparalleled, with quantities exponentially surpassing each and every ecosystem within the region and all surrounding regions.

Behavior

The fountain darter feeds on small invertebrates. It breeds all year round and the eggs are deposited on dead leaves, stems, rocks, algae or other objects. This fish lives for one to two years.

Status

They primarily occupy the sandy tops of lesser flowing springheads or flat rock surfaces absent of rooted plants, or decaying plant matter and spawn within the vibrantly abundant and healthy vegetation that thrives in these unique, pristine, springfed river systems. An extra worry for the future of fountain darters is the parasitic, non-native trematode (''

Centrocestus formosanus ''Centrocestus formosanus'' is a trematode parasite of Asian origin that has found its way into North American streams and rivers. It not only affects the fountain darter but many species of commercially important fishes. It is also capable ...

''), whose impact on the darter population is not yet known. As of 2004, only the Comal population is seriously affected by the parasite. The National Fish Hatchery and Technology Center in San Marcos keeps a reserve population of 500 adults as a hedge against a man-made or natural event wiping out the fish in the wild. The

rates this species as " Endangered". Conservation efforts include encouraging people to use less water in order to maximise water flow from the springs and to keep the rivers free from trash.

References

* * {{Taxonbar, from=Q3756372 Etheostoma Freshwater fish of the United States Endemic fauna of Texas ESA endangered species Taxa named by David Starr Jordan Taxa named by Charles Henry Gilbert Fish described in 1886